Soil acidification regulates the mobility of aluminum (Al) and manganese (Mn), thereby affecting legumes growth. Bioenergy by-products (BBP) including biochar, bottom ash and biogas slurry, can mitigate soil metal toxicity in acidic soils; however, the precise impacts of these amendments in soil-plant system remains unknown. Therefore, different treatments of BBP namely Control (T1), Biogas slurry (T2), Bottom ash (T3), Biochar (T4), Biogas slurry with bottom ash (T5), Biogas slurry with biochar (T6), Bottom ash with biochar (T7), and Biochar along with bottom ash and biogas slurry (T8) were used to mitigate the bioavailability and toxicity of Al and Mn. Results revealed that T8 reduced Al and Mn content by 63 % and 78 % in soil and 64 % and 65 % in soybean plants, respectively. Notably, T8 mitigates oxidative damage and improves rubisco activity, photosynthetic efficiency, and antioxidant activities as compared to other treatments. Furthermore, Transmission electron microscopy (TEM) shows that cell structure restoration was obvious under T6 and T8 than that of other treatments. The antioxidant genes (GmSOD, GmCAT1, and GmPOD1) and photosynthesis genes (GmRbcS and GmRCA beta) expressions were upregulated in T7 and T8 than that of other treatments. Our correlations analysis shows that BBP improved soil organic matter and further enhanced the availability of NO3-, P, and K in the soil. Furthermore, increased soil pH by BBP significantly decreased the NH4+ availability in the soil. In conclusion, our study demonstrates that BBP can enhance soybean physiological characteristics by modulating soil pH and improving nutrient availability.

The efficacy and environmental effects of using metal-organic frameworks (MOFs) for the remediation of arsenic (As)-contaminated soil, a significant global problem, remain unclear. This study evaluated MIL-88A(Fe) and MIL101(Fe) coupled with ramie (Boehmeria nivea L.) for As-contaminated soil remediation. A soil incubation experiment revealed that 10,000 mg kg-1 MIL-88A(Fe) and MIL-101(Fe) reduced As bioavailability by 77.1 % and 65.0 %, respectively, and increased residual As fractions by 8 % and 7 % through Fe-As co-precipitation and adsorption. Divergent environmental effects emerged, which were probably due to differences in the framework structures and organic ligands: MIL-88A(Fe) improved soil urease activity and bacterial diversity, whereas MIL101(Fe) induced acidification (decreasing soil pH by 25 %) and salinity stress (elevating soil electrical conductivity (EC) by 946 %). A pot experiment showed that 1000 mg kg-1 MOFs enhanced ramie biomass via As immobilization, whereas 5000 mg kg-1 MIL-101(Fe) suppressed growth because exposure to the MOF caused root damage. The MOFs enriched Pseudomonas (As-oxidizing) and suppressed Dokdonella (pathogenic), enhancing plant resilience. Notably, 100 mg kg-1 MIL-101(Fe) increased As translocation to stems (14.8 %) and leaves (27.6 %). Hydroponic analyses showed that 50-200 mg L-1 MIL-101(Fe) mitigated As-induced chlorophyll degradation (elevating Soil and plant analyzer development (SPAD) by 12.8 %-28.3 %), whereas 500 and 1000 mg L-1 induced oxidative stress (reducing SPAD by 4.2 %-10.7 %). This study provides valuable insights into using Fe-based MOFs in soil remediation and highlights their beneficial and harmful effects.

Activated coke waste (ACW), a byproduct of industrial desulfurization and denitrification, consists of fine particles ( Na+ > Cl-. Isothermal adsorption analysis revealed that Na+ and Cl- adsorption aligned with the Langmuir model, whereas SO42- adsorption adhered to the Freundlich model. Application of SACW (>= 10 g kg(-1)) effectively improved saline-alkali soil properties by lowering pH and salinity, enhancing soil aggregate stability, and promoting nutrient utilization efficiency. Notably, SACW-treated soils supported maize plants with significantly increased height and biomass (13.94% and 159.28% higher, respectively; P <= 0.05) compared to untreated controls. These benefits stemmed from improved nutrient availability and reduced salt stress-induced plasma membrane damage. These findings validate SACW as a sustainable, functional amendment for reclaiming saline-alkali ecosystems and boosting crop productivity.

Long-term exposure to Cd through contaminated food can lead to multiple adverse health effects on humans. Although previous studies have covered global food Cd concentrations and dietary Cd exposures across different populations, there are increasing concerns regarding the adequacy of current food Cd safety standards to protect populations from adverse health effects. Moreover, incorporation of Cd relative bioavailability (Cd-RBA) in foods improves the accuracy of health risk assessment. However, factors influencing food Cd-RBA have not been systematically discussed, thereby hindering its application in risk assessment. This review aims to provide an overview of Cd contents in foods, discuss concerns regarding international food Cd concentration standards, explore factors influencing food Cd bioavailability, and highlight the opportunities and challenges in refining differences between dietary Cd intakes and body burdens. Our findings suggest that current safety standards may be insufficient to protect human health, as they primarily focus on kidney damage as the protective endpoint and fail to account for global and regional variations in food consumption patterns and temporal changes in dietary habits over time. Factors such as crop cultivars and food compositions greatly influence food Cd-RBA. To improve the accuracy of Cd health risk assessment, future studies should incorporate food Cd-RBA, sociodemographic characteristics, nutritional status, and incidental Cd exposure. This review highlights new insights into food Cd safety standards and Cd bioavailability, identifies critical knowledge gaps, and offers recommendations for refining health risk assessments. This information is essential to inform future bioavailability investigations, health risk assessment, and safety standard development.

Paddy soils undergo wet-dry cycles that greatly influence the behaviour and availability of nutrients, but also of potentially toxic elements (PTEs). This study assessed the quality of paddy soils (actively cultivated and abandoned) and rice (white, brown, and wild) produced in the Baixo Vouga Lagunar (BVL) region, central-north Portugal. Surface soils were analysed for physicochemical parameters and chemical compositions, alongside sequential selective chemical extraction to evaluate metal(loid) availability. Chemical analyses were also performed on interstitial- and irrigation waters, and rice grains. The BVL soils are very strongly to moderately acidic (pH = 4.4-5.8), with organic matter contents reaching up to 34%, and exhibit a wide range of electrical conductivity values. Abandoned rice fields generally show higher values of these parameters and evidence of saline water intrusion. Several sites showed As, Cu, Pb, and U concentrations exceeding Portuguese thresholds for agricultural soils. While Cu levels were similar in both cultivated and abandoned fields, the latter had higher contents of As, Pb, and U. A geogenic origin is envisaged for these metal(loid)s, though anthropogenic contributions cannot be excluded. Sequential selective chemical extraction showed that Pb and U are strongly associated with available fractions, whereas amorphous Fe-oxyhydroxides primarily support As and Cu. Nevertheless, porewaters and irrigation waters showed low concentrations of these PTEs, suggesting minimal mobilisation to water. Furthermore, translocation to rice grains was low, with concentrations well below European Commission limits, indicating that elevated PTEs in soils do not necessarily lead to toxic levels in rice, providing reassurance regarding food safety.

Iron (Fe) deficiency is a critical constraint on global food security, particularly affecting high-value horticultural crops such as strawberries (Fragaria x ananassa). This study examines the roles of melatonin and hydrogen sulfide (H2S) signaling in mitigating Fe deficiency stress by improving Fe bioavailability and enhancing plant resilience. Strawberry plants were cultivated under Fe-sufficient and Fe-deficient conditions and treated with 100 mu M melatonin and 3 mM dl-propargylglycine (PAG), an inhibitor of L-cysteine desulfhydrase (L-DES), which regulates H2S production. Fe deficiency significantly reduced chlorophyll content and photosynthetic efficiency while elevating oxidative stress markers such as hydrogen peroxide (H2O2), malondialdehyde (MDA), and electrolyte leakage (EL). Melatonin application alleviated Fe deficiency effects by enhancing Fe utilization, stimulating L-DES activity, and promoting H2S production. Melatonin also improved antioxidant defenses by boosting the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), as well as maintaining ascorbate-glutathione (AsA-GSH) redox dynamics. The addition of 3 mM PAG inhibited L-DES activity, resulting in reduced H2S levels and diminished melatonin-induced benefits, underscoring the essential role of L-DES-mediated H2S synthesis. Despite the presence of PAG, the co-application of 0.2 mM sodium hydrosulfide (NaHS) and melatonin restored Fe bioavailability, growth, and antioxidant capacity, suggesting a synergistic interaction between melatonin and H2S. This study highlights the potential of melatonin and H2S signaling to improve Fe homeostasis and mitigate oxidative stress in Fe-deficient plants. The findings offer strategies to enhance crop resilience and productivity in nutrient-deficient soils, thereby promoting sustainable agriculture and global food security.

Globally, humans face gut microbiota dysbiosis; however, its impact on the bioavailability of cadmium (Cd) and arsenic (As) from rice consumption-a major source of human exposure to these metals-remains unclear. In this study, we compared Cd and As accumulation in the liver and kidneys of mice with disrupted gut microbiota (administered cefoperazone sodium), restored microbiota (administered probiotics and prebiotics following antibiotic exposure), and normal microbiota, all after consuming cocontaminated rice. Compared to normal mice, microbiota-disrupted mice exhibited 30.9-119% and 30.0-100% (p < 0.05) higher Cd and As levels in tissues after a 3 week exposure period. The increased Cd and As bioavailability was not due to changes in the duodenal expression of Cd-related transporters or As speciation biotransformation in the intestine. Instead, it was primarily attributed to a damaged mucus layer and depleted tight junctions associated with gut dysbiosis, which increased intestinal permeability. These mechanisms were confirmed by observing 34.3-74.3% and 25.0-75.0% (p < 0.05) lower Cd and As levels in the tissues of microbiota-restored mice with rebuilt intestinal barrier functions. This study enhances our understanding of the increased risk of dietary metal(loid) exposure in individuals with gut microbiota dysbiosis due to impaired intestinal barrier functions.

AimTo examine the effect of active aluminum (Al) on copper(II) (Cu(II)) bioavailability in an acidic Cu-contaminated soil and uptake of Cu(II) by Chinese cabbage.MethodsA pot trial was conducted with Ca(OH)2 and peanut straw biochar (PB) to investigate Cu(II) uptake by Chinese cabbage. DGT (CDGT-Cu) and CaCl2 extraction methods (CCaCl2-Cu) were used to determine soil available Cu(II) and BCR sequential-extraction was used to determine Cu(II) species in the soil.ResultsThe amelioration of soil acidity with Ca(OH)2 and PB increased soil pH, promoted Chinese cabbage growth, and decreased Cu(II) uptake by plant shoots/roots. There were highly significant positive linear correlations between CDGT-Cu, CCaCl2-Cu and Cu(II) uptake by plant shoots. CDGT-Cu showed a better predictive effect for Cu(II) uptake by plant roots with a greater correlation coefficient (R2 = 0.9756). Thus, the DGT method was more effective in predicting Cu(II) uptake by plants. With increasing soil pH, Cu-HOAc and Cu-Reducible were converted to Cu-Residual, resulting in a decrease in soil Cu(II) bioavailability. The results of Structural Equation Modeling analyses showed that Al uptake by Chinese cabbage had a promoting effect on Cu(II) uptake by the plant, mainly through affecting plant growth indirectly. Soil exchangeable Al inhibited root growth (root length, root dry weight), reduced root resistance of Chinese cabbage and indirectly increased Cu(II) uptake.ConclusionsReducing Al toxicity decreased root damage and Cu(II) uptake by plant, improving the edible quality of Chinese cabbage. When remediating acidic Cu-contaminated soils, more attentions should be payed to mitigating and regulating Al toxicity.

Arsenic is a well-known toxic substance, widely distributed, whereas vanadium is a pollutant of emerging interest. Both have been found to correlate positively in groundwaters, thus concern arises on the effect of these pollutants on crops, if such waters are used for irrigation. We conducted a study on the effect of aging with a typical crop soil mimicking soils initially irrigated with water containing As and V. Afterwards, the soil was subjected to wet/dry cycles. The fractionation of both elements at different times from the addition (onset of the experiment) was determined by a modified European Community Bureau of Reference (BCR) method. It is found that the greater part of V is located in the most stable fraction from the onset of the experiment. This is attributed to interaction with amorphous and clay minerals and the precipitation of Ca(VO3)2, which is predicted by speciation modeling. The remaining fractions show the expected behavior: the most labile fraction decreases over time, that associated to oxidizable increases with time, whereas the fraction associated to reducible components stays approximately constant. Arsenic shows a lower proportion in the most stable fraction compared with V, and a higher proportion in the most labile, but otherwise shows similar tendencies. The results suggest a low availability of V and a higher one of As. No competence was observed between As and V in the experimental conditions.

PurposeDeveloping a practical strategy for both remediating and utilizing Cd-contaminated soils is important, particularly in areas with limited soil resources. Here, Erigeron breviscapus, a plant material used for extracting scutellarin, was selected for a pot experiment to evaluate utilization and remediation potential of heavily Cd-contaminated soil. MethodsWe established five treatments, comprising a no-Cd added control (CK) and 0.01% Cd addition with four amounts of lime (0, 5, 15 and 20 gkg-1 for CdL0, CdL5, CdL15 and CdL20, respectively). Systematic analysis of E. breviscapus physiological and biochemical characteristics, Cd-accumulation capacity, and active ingredients content were performed to thoroughly assess the application effectiveness and ecological restoration potential of lime in managing heavily Cd-contaminated soils. ResultsCompared with CdL0, lime application (CdL5, CdL15 and CdL20) reduced soil available Cd and plant shoot-Cd concentrations by 19.2-29.4% and 29.3-36.3%, respectively, due to decreased bioconcentration factor. Soil-Cd concentrations after harvesting E. breviscapus was decreased by 11.8-31.7% with lime application compared with that before cultivation. In the CdL0 treatment, biomass and scutellarin content of E. breviscapus decreased compared to those of the CK. However, plant biomass and scutellarin content increased with CdL15 and CdL20 compared to CdL0. Structural equation modeling indicated that lime application reduced plant Cd uptake via regulating soil-Cd speciation, thereby alleviating damage caused by Cd to photosynthesis, antioxidant system, and Mg acquisition, ultimately increasing biomass and scutellarin content of E. breviscapus. ConclusionsIn summary, growing E. breviscapus after lime application is a feasible method for remediating and utilizing heavily Cd-contaminated soil.